Learn how to rebuild a 4L60 and 4R70W series automatic transmission --

This gentleman is an excellent teacher -- he obviously has been doing transmissions for a long time. He has multiple in-depth videos on how to rebuild the 4L60 and it's variants (I've rebuilt one of those, and wish I had seen this vid before I started), and the 4R70W.

He's just getting started on YouTube, but his vids are very professionally done, and the explanations are thorough. It's a must view for any gearhead